What is the grammatical parsing (إعراب) of the word of majesty "Allah" in the phrase "There is no god but Allah," and is it pronounced with a dammah (ضمّة) or a fatha (فتحة)?

The word of majesty (Allah) in the declaration of faith "LāʾilāhaʾillāAllāh" (There is no god but Allah) is parsed as a substitute for the hidden pronoun "He" in the omitted predicate, which is understood to be "Haqq" (true) or "Mawjūd" (existent). It is in the nominative case, and its sign of being so is the explicit damma. It is worth noting that it is permissible for the noun following "illā" in the declaration of faith to be in either the nominative or accusative case outside of the Quran, with the nominative being more common.